The central focus of this research plan is to define further the metabolism of lead (Pb) in bone, where chelating agents exert their major effects, and in children, where Pb is drawn to sites of rapid bone remodeling. The major methodological approach is to isolate specific bone cells: osteoclasts (CT) and osteoblasts (PT) from mouse calvaria. By so doing, the transport of preincorporated 203Pb, the distribution of Pb in bone, the influences of chelating agents, the concentration of trace metals, the morphogenesis of Pb inclusions, the effects of calcium-regulating hormones, the activation of acid and alkaline hydrolases, the impact on the synthesis of hyaluronic acid and decarboxylation of citrate, and the effects on cAMP production can be examined at the cellular level. Companion studies in bone organ culture will investigate the early morphogenesis of Pb inclusions coupled with changes in 203Pb transport and the activities of bone hydrolases. The distribution and transport of 203Pb in the red cell (RBC) spectrin-actin lattice will be clarified by separation of membrane components (bidimensional flatbed isoelectric focusing) from pre-labelled RBC's. Further studies of the kinetics of this transport system will be carried out by reconstitution of the membrane components into membrane vesicles. Clinical studies will measure, by proton-induced x-ray emission, trace metal metabolism in children undergoing chelation therapy. In addition, further clarification of Pb's impairment of the biogenesis of 1,25-dihydroxyvitamin D3 will be sought in children who have increased Pb absorption.